1. Field of the Invention
The present invention relates generally to field of self-propelled, land vehicles primarily used for transportation of people and cargo on improved road surfaces (commonly referred to as the automotive field, but including trucks, buses and specialty vehicles). More particularly the present invention relates to what are frequently called hybrid vehicles, namely those which use two or more distinct power sources to propel the vehicle. As one of the power sources of the vehicle of the invention is electric it relates to the field of hybrid-electric vehicles. As one of the power sources of the invention is a Stirling Cycle Engine, which said engine may be operated on a wide variety of liquid fuels the invention also relates to the field of flexible fuel hybrid-electric vehicles. As the invention also includes a Thermoelectric Generator and Regenerative Braking it also relates to those field.
2. Description of Related Art
Early in the field of automotive design engines which run on the Stirling Cycle (hereinafter called “Stirling Engines”) were tried and did demonstrate some utility. However use of such engines for automobiles was subsequently abandoned in favor of internal combustion engines, despite the fact that Stirling Engines pose the potential for the greatest fuel efficiency of any of the real heat engine designs, have few noxious emissions and can be run on a variety of fuels. It appears that this abandonment resulted from the fact that Stirling Engines could not generate useful amounts of power immediately after cold start (but must be heated to operating temperature, in contrast with internal combustion engines which can generally be used immediately after starting) and the fact that Stirling Engines are not very responsive to varying power demands (accelerate and decelerate at significantly slower rate than internal combustion engines).
While significantly more “responsive” than Stirling Engines, internal combustion engines possess certain undesirable characteristics, including considerably worse fuel economy, greater emission of noxious exhaust gases (including oxides of nitrogen and carbon) and each are designed to operate on a very narrow range of fuel. As long as all forms of fuel for internal combustion engines was cheap and plentiful, and the consequences of noxious exhaust gases was not well appreciated, the use of the internal combustion engine was the preferred automotive engine. Now that fuel is becoming increasingly scarce and very expensive and the consequences of atmospheric pollution becoming increasingly appreciated, decreased use of the internal combustion engine would appear to be highly desirable. Yet the undesirable characteristics of using a Stirling Engine to drive automobiles remained to be over-come. The invention described and claimed herein employs use of a Stirling Engine in the automobile but uses it in a way that over-comes the undesirable characteristics of the Stirling Engine previously encountered in such use.
Similarly there has been some, but not widespread, use of electric motors to drive automobiles. In general electric drive motors have been used in “all electric” cars and in “hybrid-electric” vehicles that employ the internal combustion engine either to drive the driven wheels of the vehicle, to charge the battery of the vehicle or some combination of both.
“All electric” vehicles, which are driven by electric motor which draws electricity from a non-board battery suffer certain disadvantages which limit their utility. Principally these limitations relate to the limited range that may be obtained from on-board battery which is of reasonable size, weight and expense, coupled with the long time required to recharge an exhausted battery (or the impracticalities involved in changing replacing exhausted battery with a charged battery).
“Hybrid-electric” vehicles which employ the use of an electric motor to drive the vehicle and an internal combustion engines (to charge the battery of the vehicle or when extra power is needed) have had some success, mainly derived from their use of a smaller internal combustion engine, shutting same down when the vehicle is at idle and use the use of regenerative braking (whereby upon braking the automobile is used as a generator to charge the battery of the vehicle), but suffer at least some degree of the disadvantages of internal combustion engines mentioned above (poor fuel efficiency, higher undesirable emissions and largely inflexible fuel requirements).
In the last two decades there appears to have some experimentation with development of a hybrid-electric vehicle that employs use of a Stirling Engine to generate electricity which charges the battery of the vehicle, delivers electric power to the automobile of the vehicle but it appears that such experimentation was unsuccessful because of a variety of problems including lower-than-expected thermal efficiency, high heat rejection requirements, poor specific power, and excessive hydrogen leakage.
At the same time improvements in thermoelectric generating devices have improved the cost, efficiency and size of such devices, making it possible that waste heat can now be practically employed to generate useful quantities of electrical power.
It does not appear that all of the advances in technology which have recently taken place, including reducing the size, weight and electrical storage capacity of batteries; improvements in the design of automobiles, including reduction of their size, weight and efficiency; improvements in solid state switching of heavy electrical currents; improvement in Stirling Engines; use regenerative braking technology; and, improvements in thermoelectric generators have been brought together to create a hybrid-electric automobile drive system which is operable on a wide variety of liquid fuels, provides for substantial increases in fuel economy and is less polluting of the atmosphere.